The following information is provided to assist the reader in understanding technologies disclosed below and the environment in which such technologies may typically be used. The terms used herein are not intended to be limited to any particular narrow interpretation unless clearly stated otherwise in this document. References set forth herein may facilitate understanding of the technologies or the background thereof. The disclosure of all references cited herein are incorporated by reference.
A self-contained breathing apparatus (“SCBA”) is a device used to enable breathing in environments which are immediately dangerous to life and health (sometimes referred to as “IDLH” environments). For example, firefighters wear an SCBA when fighting a fire. The SCBA typically has a harness or carrier system including a backplate supporting an air tank or cylinder which is connected to a user interface such as a mouthpiece or a facepiece, all of which are worn or carried by the user. The tank typically contains air or oxygen-containing breathing gas under high pressure (for example, 2200-5500 psi or 15,168 to 37921 kPa) and is connected to a first stage regulator which reduces the pressure to about 80-100 psi or 552 to 689 kPa. The SCBA usually has a second stage regulator that has an inlet valve which controls the flow of air for breathing between the air tank and the facepiece. Typically, the inlet valve controls the flow of air through the second stage regulator in response to the respiration of the user. Such respiration-controlled regulator assemblies are disclosed, for example, in U.S. Pat. Nos. 4,821,767 and 5,016,627, the disclosures of which are incorporated herein by reference.
Currently available SCBAs and other breathing apparatuses include multiple fastening components to position and attach pneumatic and/or electronic components (for example, connectors, hoses, cables etc.) to the backplate. Accessing multiple fastening components impedes the assembly and removal of pneumatic and/or electronic components. Moreover, pneumatic and/or electronic components and their associated connections are left substantially unprotected or underprotected in some currently available systems. As a result, the pneumatic and/or electronic components and connections may be subject to significant impact and environmental exposure. Often, materials for pneumatic and/or electronic components and their associated connections must be selected to endure substantial environmental exposure and impacts, adding cost and weight to the breathing apparatus.
Problems also arise in currently available breathing apparatuses as a result of differently sized tanks. For example, making a connection between the tank/cylinder valve outlet and the first stage regulator is difficult because the distance therebetween changes with differently sized tanks. The variable distance may, for example, require the use of different high-pressure hose assemblies having different lengths and/or configurations. A number of breathing apparatuses include a first stage regulator assembly that is variable in position (for example, sliding or floating) to adjust the distance between the outlet of the tank valve and the connector for the first stage regulator. Such an approach requires the first stage regulator assembly to move up and down and/or forward and back to connect to different diameter tanks. Hoses exiting the first stage regulator (for example, a second stage regulator hose and/or a gauge hose) in such systems must be able to move relative to the backplate and/or shoulder straps. Moving the hoses varies effective hose length and/or configuration, which may adversely impact user interfaces. Moreover, a movable first stage regulator assembly may not be suitably structurally supported, and clearance space must be provided to accommodate motion of the movable first stage regulator assembly.
A number of breathing apparatuses use a tank/cylinder connection that articulates to accommodate different size tanks. Such systems require that the connection include multiple components and high pressure seals to allow the tank connection to be positioned properly relative to different size tanks. The additional components and seals increase design complexity and cost, while introducing additional high-pressure seal leakage risks. An articulating tank connection may further hinder the user's ability to properly position and engage the cylinder valve.
Various abutment geometries may be used to contact the tank to position the tank relative to the backplate. However, the geometries of tanks vary significantly (for example, as a result of different pressure ratings, construction materials, and manufacturing processes). The variability in tank geometries makes it very difficult to appropriately control the position of tanks via abutments or stops.
The variability in tank size and geometry also affects the connection of the tank to the backplate and the orientation of the tank relative to the backplate. Widely varying tank geometry and size may, for example, cause the tank to be angled relative to the backplate and result in an increased profile (thereby increasing the likelihood of catching or entanglement in confined spaces). Currently available connectors and/or abutments used to position tanks have limited success because of the variability in tank geometries discussed above.